Abstract
Galacto-oligosaccharides (GOS) and fructo-oligosaccharides (FOS) are food ingredients that improve human health, but their degradation throughout the human small intestine is not well understood. We studied the breakdown kinetics of FOS and GOS in the intestines of seven healthy Dutch adults. Subjects were equipped with a catheter in the distal ileum or proximal colon and consumed 5 g of chicory-derived FOS (degree of polymerization (DP) DP2-10), and 5 g of GOS (DP2-6). Postprandially, intestinal content was frequently collected until 350 min and analyzed for mono-, di-, and oligosaccharides. FOS and GOS had recoveries of 96 ± 25% and 76 ± 28%, respectively. FOS DP ≥ 2 and GOS DP ≥ 3 abundances in the distal small intestine or proximal colon matched the consumed doses, while GOS dimers (DP2) had lower recoveries, namely 22.8 ± 11.1% for β-D-gal-(1↔1)-α-D-glc+β-D-gal-(1↔1)-β-D-glc, 19.3 ± 19.1% for β-D-gal-(1 → 2)-D-glc+β-D-gal-(1 → 3)-D-glc, 43.7 ± 24.6% for β-D-gal-(1 → 6)-D-gal, and 68.0 ± 38.5% for β-D-gal-(1 → 4)-D-gal. Lactose was still present in the distal small intestine of all of the participants. To conclude, FOS DP ≥ 2 and GOS DP ≥ 3 were not degraded in the small intestine of healthy adults, while most prebiotic GOS DP2 was hydrolyzed in a structure-dependent manner. We provide evidence on the resistances of GOS with specific β-linkages in the human intestine, supporting the development of GOS prebiotics that resist small intestine digestion.